Electrochemical Properties of LiCo0.4Ni0.6O2 and its Performances in Rechargeable Lithium Batteries

Intercalation cathode materials belonging to the 4-volt class electrodes, lithiated cobalt oxide LiCoO₂ and lithiated nickel cobalt oxide LiCo_0.4Ni_0.6O₂, were synthesized by sol-gel technique. The structural characteristics of the compounds were studied using XRD, FTIR and DSC. The compounds were used as cathode materials for assembling rechargeable lithium-batteries and their electrochemical performances were studied. The potentiostat and galvanostat techniques were used to determine the electrochemical characteristics. The irreversible capacity loss of LiCoO₂ during the first charge-discharge is about 20% and for LiCo_0.4Ni_0.6O₂ is about 90% for two different current rates of 5 and 10 A kg^-1. The overall electrochemical capacity of LiCo_0.4Ni_0.6O₂ has been drastically reduced due to the s-block or p-block metal substitution. Also the un-reacted materials remained as impurities gave a very poor cycleability. However more stable charge-discharge performances have been observed for LiCoO₂ at different current rates. Differences and similarities between these two cathode materials in batteries are also discussed. The Li-ion batteries were assembled using the sol-gel synthesized cathode materials, natural untreated vein graphite of Sri Lanka as the anode material and 1 M LiPF₆ in EC/DMC as liquid electrolyte, and their performances were tested.  

doi:10.4038/sljp.v8i0.213  

Sri Lankan Journal of Physics, Vol. 8 (2007) 47-58